Agg2 will not compute because ClientDataset index is set to ClientDataSet1Index1.
if ClientDataset.IndexName = ClientDataSet1Index2, Agg2 works, but Agg1 doesn't :(
It doesn't seems to allow multiple groupinglevels since I can only
specify one clientdataset index at a time.

Am I missing something ?

The workaround is to clone my
clientdataset and create the other
aggregate in there. Bit of an inconvenience.